Attractivity and social preferences in mice (Mus musculus domesticus): the role of prepubertal sexual segregation and of precocious weaning.

Mice (Mus musculus domesticus) were raised (Postnatal Day 15 to 25) in single- or mixed-sex litters and precociously (Day 15) or regularly (Day 25) weaned. When they were faced as adults with a basic social choice--between two stimulus mice raised in litters of different sex composition but both of the same sex as the chooser--mice raised in mixed-sex litters were preferred. In the sociosexual choice-between a male and a female, both from the single- or the mixed-sex group--the opposite-sex preference was expressed. Both these preferences were abolished by the sexual segregation of the choosers. This variable hardly affected potential mate choice--between two stimulus mice both of the opposite sex of the chooser but raised in litters of different sex composition. Data indicate that socially mediated behavioral plasticity has a major role in the early shaping of adult individual differences both in attractive stimulus properties and in sociosexual preferences.

Prenatal cocaine potentiates the effects of morphine in adult mice.

Prenatal cocaine exposure has been reported to result in abnormal neurobehavioral development, both in animals and humans. In this study, outbred CD-1 mice were exposed in utero to cocaine hydrochloride administered daily as i.p. injections to dams from day 10 of gestation to day 16, at the dose 0, 5 or 50 mg/kg. Cocaine did not alter duration of pregnancy while it decreased the difference in maternal body weight from days 10 to 16 in the dams receiving the higher dose of cocaine. The body weight of the offspring from birth to 15 days of age and the physical maturation were not affected by prenatal cocaine exposure. The development of the response to strong tactile stimulation was either slightly delayed in the 5 mg/kg group or markedly accelerated in the 50 mg/kg group. At adulthood, animals were assessed for behavioral responses to a novel environment, for response to painful stimulation (hot-plate test set at 55 +/- 1 degree C), and for the effects of a single morphine injection (30 mg/kg, i.p.). Data showed that in the absence of prenatal cocaine exposure effects, morphine increased the time spent in inactivity, while it decreased rearing, grooming and bar-holding behaviors. In the case of sniffing, morphine increased this behavior, except in the 5 mg/kg cocaine group. Moreover, morphine administration induced the expected increase of locomotion, irrespective of prenatal condition. With respect to pain reactivity, prenatal cocaine exposure resulted in an increase of licking latency in the 5 mg/kg group.(ABSTRACT TRUNCATED AT 250 WORDS)

Sexual segregation in infancy and bi-directional benzodiazepine effects on hot-plate response and neophobia in adult mice.

In the present experiment, the hypothesis that rearing animals in conditions of sexual segregation in infancy (ISS) would affect their adult behavioral reactivity to drug or environmental challenges was tested. Outbred Swiss CD-1 mouse litters were reduced at birth to six pups according to three conditions: MM (all males), MF (sex-balanced composition), and FF (all females). At weaning (day 21), all mice were rehoused in unisexual groups. At adulthood (day 70), animals were challenged either with BDZ agonist chlordiazepoxide (CDP at 2.5- or 5.0-mg/kg dose) or BDZ receptor partial inverse agonist Ro 15-3505 (RO at 3-, 10-, or 30-mg/kg dose) and assessed in sequence for pain reactivity in a hot-plate apparatus (set at 55 +/- 1 degrees C), for locomotor activity in a Varimex apparatus, and finally for neophobia level by measuring the latency to first approach a novel object. As concerns the hot-plate test, lick latency was significantly shortened in MF females receiving CDP (5.0 mg/kg), while RO was either ineffective in MF females or induced a prominent dose-dependent analgesia in FF females. Activity was decreased by CDP (2.5 mg/kg) and enhanced by RO (3.0 mg/kg). For latency to approach a novel object, males as a whole exhibited shorter times than females. Mixed-sex animals of both sexes were less fearful, being also more explorative than their corresponding unisexually reared groups. In particular, MF males receiving either a 5.0-mg/kg CDP dose or a 3.0-mg/kg RO dose explored the object more often than MM males.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification and partial characterization of a new 85 KDa amyloidosis-related protein in chronic hemodialysis.

An 85 KDa protein was purified by a multistep procedure (ultracentrifugation, HPLC, SDS-PAGE) from sera and amyloid deposits of patients on chronic hemodialysis and was characterized as a novel protein on the basis of its NH2 terminus (KVQLVE-V). This protein was formed by two subunits with Mr of 55 and 30 KDa and had affinity for Thyoflavin T, a fluorescent dye which was employed for labelling the protein prior HPLC. The 85 KDa was the only fluorescent component of ultracentrifugates from the serum of hemodialyzed patients while in amyloid fibrils it coexisted in roughly equimolar amounts with beta 2-microglobulin. This new high molecular weight protein which accumulates in uremia, could be co-responsible with beta 2-microglobulin for hemodialysis-related osteoarticular amyloidosis.

Morphine effects on mouse locomotor/exploratory activity: test dependency, test reliability, uni- and multi-variate analyses.

Drug and toxicant effects on locomotor/exploratory activity can be quite variable depending on the test and the schedule of exposure. In neurobehavioral toxicology and teratology, these interactions can affect the inferences based on the use of selected drugs as probes to assess which regulatory mechanisms are affected by one or the other treatment. The present experiments were aimed at comparing morphine effects in CD-1 mice under three conditions, namely, Varimex apparatus (VAR), toggle floor box (TOGGLE), videotape recording (VIDEO) in a home cage environment. Morphine HCI (0, 10, 33, or 100 mg/kg) was given IP 20 min before the start of a 30-min test session. The same procedure was repeated 24 h later. Results of VAR and TOGGLE tests were: dose 10 was largely ineffective; dose 33 induced depression in VAR and hyperactivity in TOGGLE; dose 100 enhanced activity in TOGGLE. There were no differences between session 1 and 2. VIDEO: Univariate analysis results showed that morphine produced a dose-dependent depression of Rearing and Grooming, and an enhancement of Crossing, again without changes due to repeated exposure. Results of Principal Component Analysis supported a response competition model of the changes observed in the mouse behavioral profile. The videorecording (VIDEO) procedure is the one providing the most accurate picture of changes in locomotor/exploratory activity and drug effects thereon, also allowing a more comprehensive statistical analysis of the relationships between various types of response changes.

Allergy and asthma: distinguishing the causes from the triggers. An eye model for the study of inflammatory events following allergen challenge.

The study of the late-phase reaction to allergen challenge has greatly contributed to increasing understanding of the relationship existing between immunoglobulin E (IgE) triggering, allergic inflammation and bronchial hyperreactivity, as well as to changing our concept from "causes" to "triggers" of asthma. This paper reviews personal studies on a model of conjunctival provocation in allergic subjects. These studies represent the first evidence of a late-phase reaction in the human eye and contribute to a better knowledge of the network of cells and mediators involved in allergic inflammation which are responsible for heightened bronchial reactivity in allergic asthma.